Forming Touch Fasteners on Substrates

ABSTRACT

A touch fastener strip includes a sheet-form material substrate having a front face, an array of fastener elements integrally molded with a resin base layer on the front face of the substrate and an array of discrete regions of resin (e.g., gripping elements) integrally molded with a resin base layer through apertures in the sheet-form material on the back face of the substrate. The array of fastener elements forms a discrete band of fastener elements extending longitudinally along the front face of the fastener strip, and the array of gripping elements forms a discrete band of gripping elements extending longitudinally along the back face of the fastener strip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. patent application claims priority under 35 U.S.C. §119(e) toa U.S. provisional patent application 60/971,469 filed on Sep. 11, 2007,the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

This invention relates generally to forming touch fasteners onsubstrates and methods and apparatus for their manufacture.

BACKGROUND

Early touch fastener systems featured two mating tapes, each being knitor woven. One tape would include loops of filament woven into a base,and the other would include filaments woven to form loops and then cutto form hooks.

More recently, continuous molding of fastener elements extending from acommon sheet-form resin base has resulted in less expensive and thinnerhook fastener tapes. Significant improvements in this area include thedevelopment of continuous fastener tape molding using fixed moldcavities (see Fischer, U.S. Pat. No. 4,794,028). Further improvementshave reduced the size of the fastener elements moldable by suchtechniques, to heights of 0.015 inch or less, which provide a verysmooth touch when arranged in dense arrays.

As molded fastener tape has been improved to be more flexible and lessexpensive, it has found application in disposable garments, such asdiapers. In typical diaper applications, a fastening tab is formed witha continuous strip of fastener tape, which includes lanes of hooks,laminated to the tab substrate.

SUMMARY

The invention enables, in several of its aspects, a touch fastenerproduct having a band of hooks extending from a front face of asheet-form material substrate and a band of grip dots extending from aback face of a common sheet-form material substrate. Among otherapplications, this product can be included on disposable garments tofunction as a closure tab.

According to one aspect of the invention, a touch fastener stripincludes a sheet-form material substrate having a front face, an arrayof fastener elements integrally molded with a resin base layer on thefront face of the substrate and an array of gripping elements integrallymolded with a resin base layer through apertures in the sheet-formmaterial on the back face of the substrate. The array of fastenerelements forms a discrete band of fastener elements extendinglongitudinally along the length of the front face of the fastener strip,and the array of gripping elements forms a discrete band of grippingelements extending longitudinally along length of the back face of thefastener strip.

In some cases, the fastener strip is constructed where the fasteningelements are not directly opposite the gripping elements.

According to a second aspect of the invention, a method of fabricating atouch fastener product is provided. The method includes steps of feedingflowable resin and sheet-form material into a nip between two rotatingrolls including a mold roll defining an array of cavities extendinginward from a peripheral roll surface, and forming a base layer of resinlaminated to the sheet-form material under pressure in the nip whilemolding an array of discrete projections of the resin in the cavities,such that the projections and the base layer form a seamless mass of theresin, and forming engageable heads of the resin on the projections,thereby forming an array of fastener elements extending from the baselayer, and forming an array of discrete regions of the resin on a sideof sheet-form material opposite the projections, each discrete regioncomprising exposed resin surrounded by exposed sheet-form material, thediscrete regions formed of resin pressed through apertures defined inthe sheet-form material by pressure in the nip, and cooling the resin tosolidify the projections, and releasing the cooled resin from the moldroll.

In some methods, the engageable heads of the fastener elements areformed while molding the discrete projection of the fastener elements.In some cases, the fastener elements are J-hook shaped.

In some methods, the engageable heads and the discrete projection of thefastener elements are not molded and formed, respectively,simultaneously. In some cases, the fastener elements aremushroom-shaped.

In some methods, the resin forming the discrete region flows throughapertures defined by severed edges of the sheet-form material.

In some methods, prior to feeding the sheet-form material into the nip,the method includes cutting apertures into the sheet form material. Insome cases, the apertures are cut so as to form an evenly spaced arrayof apertures.

In some methods, at least some of the discrete projections are directlyopposite respective discrete regions.

In some methods, the discrete projections and the discrete regions areseparated by a lane of resin-free sheet-form material.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of the front face of a touch fastenerproduct.

FIG. 1A is an enlarged perspective view of a portion of an array ofhook-shaped fastener elements.

FIG. 2 is a perspective view of the back face of a touch fastenerproduct in the form of a disposable garment tab.

FIGS. 3-5 are cross-sectional views and illustrate examples of a touchfastener product in the form of a disposable garment tab.

FIG. 6 illustrates a first method and apparatus for forming touchfastener products.

FIG. 7 illustrates a second method and apparatus for forming touchfastener products.

FIG. 7 a illustrates an expanded view of a selected portion of FIG. 7.

FIG. 8 illustrates a third method and apparatus for forming touchfastener products.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIG. 1, a lengthwise-continuous touch fastener strip 10,such as for disposable garments, includes a thin, sheet-form materialsubstrate 12 with a lengthwise-continuous stripe of a resin base layer14 and parallel bands 16 and 18 of fastener elements attached to thestripe 14 on its front face 20. Bands 16 and 18 are equally spaced fromthe center “C” of the fastener strip and base layer 14 extendscontinuously from the outer edge of band 16 to the outer edge of band 18in this example. The fastener elements 22 of bands 16 and 18 areintegrally molded with base layer 14 and extend from front face 18. FIG.1A illustrates the fastener elements 22 in this example, which are inthe form of J-hooks 24 that extend, in rows, along the length of theclosure strip. Some of the J-hooks 24 face in opposite directions alongthe strip. Other fastener element shapes may also be employed (notillustrated), including those that are in the form of mushroom-shapedprojections. A suitable fastener element shape is the CFM29 hook shape(of about 0.015 inch in height), available in various products sold byVelcro USA in Manchester, N.H.

Referring to FIG. 2, the back face 26 of a lengthwise-continuous touchfastener strip 10 has lengthwise-continuous, band 28 of grippingelements 32. Band 28 is centered along the center “C” of the fastenerstrip and extends from the inner edge of band 16 to the inner edge ofband 18. The gripping elements 32 of band 28 are integrally molded withbase layer 14 through apertures 30 in material substrate 12 and extendfrom back face 26. In this embodiment, these gripping elements are inthe form of half spheres that extend, in rows, along the length of theclosure strip. Other gripping element shapes may also be employed,including those that are flush with the surface of the sheet-formmaterial substrate 12. In one suitable arrangement, the grippingelements 32 are circular dots of resin, each having a diameter ofbetween about 1.5 to 2.5 millimeters, and spaced evenly in an array witha dot center-to-center distance of between about 6 and 12 millimeters.

The dotted lines in FIGS. 1 and 2 illustrate a cutting pattern forseparating strip 10 into individual fastening tabs. The cutting patternincludes transverse cuts that intersect a longitudinal serpentine cutextending along the center “C” of the strip. The cuts are arranged suchthat each separated fastening tab includes a region of fasteningelements on one side, near one end of the tab, and a region of grippingelements on an opposite side of the tab.

FIGS. 3 through 5 are transverse cross-sections of examples of fasteningtabs separated from suitable configured fastener strips. In FIG. 3,fastener tab 110 a has a single stripe of resin base layer 200, fromwhich both the fastener elements 22 and gripping elements 32 extend toform a single, seamless, contiguous mass of a single resin or blend ofresin. The left end of base layer 200 in this example is severed andcoincides with the severed end of the underlying substrate 26. Thefastener elements 22, as shown, are not directly opposite the grippingelements 32. Tab 110 a is formed by cutting the fastener strip of FIGS.1 and 2 along the illustrated cut lines. In FIG. 4, fastener tab 110 bhas a single, longitudinally continuous base 200 b formed as aco-extrusion or lamination of two layers of resin: an upper resin layer208 of a resin or resin blend common with the fastener elements, and alower resin layer 210 of a resin or resin blend common with grippingelements 32 a. In this manner, the fastener elements 22 may be provideddirectly opposite the gripping elements 32 a, while the resin of the twobase layers can be selected for optimum performance of its integralfeatures. In other words, the resin of layer 208 may be selected foroptimum fastener element performance, while the resin of layer 210 maybe selected for optimum formation and function of gripping elements 32.FIG. 4 also shows that gripping elements 32 a may be configured toextend laterally beyond their associated substrate apertures 30, with‘rivet-shaped’ heads. In FIG. 5, example 10 c of fastener product 10 hastwo stripes of base layer 200 c and 200 a, respectively. One stripe ofbase layer 200 a carries fastener elements 22. At the opposite surfaceof a separate base layer 200 c are gripping elements 32 b in the form ofexposed, spaced apart resin surfaces coplanar with the surroundingsubstrate surface 26. A lane 206 of resin-free substrate material 12separates the two stripes of base layer 200 and 200 a, which may beoptimally formed of different resins selected for fastening andgripping, respectively. Another resin-free lane 212 of substrate. 12 atthe distal end of tab 110 c is formed by cutting the substrate betweenspaced-apart longitudinal bands of gripping element resin in thefastener strip as initially formed. In the examples of FIGS. 3 and 5,the upper, exposed surface of the base resin layer opposite the grippingelements forms an opposing grip surface, and may be molded or otherwiseformed to have a suitable grip texture. In each of these examples, thebase layers may be longitudinally continuous along the sheet, or maycomprise longitudinally spaced-apart sections or islands of basematerial surrounded by exposed material 12, to provide moretouch-friendly severed tab edges. Additionally dashed line 214 of FIG. 3illustrates that the thickness of base layer 200 may be molded to taperto a very narrow edge where severed, to help avoid a rough distal tabend. Such tapering may be accomplished during molding by a suitablyconfigured splitting feature, such as a V-shaped circumferentialprotrusion, extending from the mold roll of FIG. 6 and arranged tofollow the center cut line of the fastener strip.

FIG. 6 illustrates one method and apparatus for producing theabove-described fastener strips. The method builds upon the continuousextrusion/roll-forming method for molding fastener elements on anintegral, sheet-form base described by Fischer in U.S. Pat. No.4,794,028, and the nip lamination process described by Kennedy, et al.in U.S. Pat. No. 5,260,015, the details of both of which areincorporated herein by reference. The relative position and size of therolls and other components is not to scale. An extrusion head 300supplies a continuous sheet of molten resin to a nip 302 between arotating mold roll 304 and a counter-rotating pressure roll 306. Moldroll 304 contains an array of miniature, fastener element-shaped moldcavities 305 extending inward from its periphery for molding thefastener elements. Pressure in nip 302 forces resin into the fastenerelement cavities and forms the substrate. Along with the molten resin, acontinuous sheet-form material 310 is fed into nip 302, where it ispartially impregnated by resin and becomes permanently bonded to theresin base layer. As supplied to the nip, substrate material 310 ispre-perforated, such that the substrate defines an array of discreteapertures where the gripping elements are to be formed. Pressure in nip302 forces resin through the apertures in the sheet-form material andforms the gripping elements. The formed product is cooled on the moldroll until the solidified fastener elements (e.g., hooks) are strippedfrom their fixed cavities by a stripper roll 308. Thus, the completedfastener product 312, which is stripped from the mold roll, includesboth fastener elements and gripping elements on the sheet-form material.To form the various tab and strip configurations disclosed herein, theresin may enter the nip in parallel, spaced apart bands or islands, asdisclosed in Krantz et al., U.S. Pat. No. 7,048,818, also incorporatedherein by reference.

FIG. 7 illustrates a variation of the above-described method. In thiscase, rather than forming gripping elements flush with the surface ofthe sheet-form material with a pressure roll that has a smooth surface,a pressure roll 306 a containing an array of miniature, grippingelement-shaped mold cavities extending inward from its periphery is usedto form half-spherical gripping elements protruding from the surface ofthe sheet form material. In FIG. 7A, sheet-form material 310 is lined upwith pressure roll 306 a, such that the apertures 314 in the sheet-formmaterial line up with gripping-element shaped cavities 316 as to allowresin to fill the gripping-element shaped cavities. Referring back toFIG. 7, pressure in nip 302 simultaneously forces resin into thefastener element cavities and forms the substrate on one side of thesheet-form material and through apertures in the sheet-form materialinto the gripping-element cavities on the opposite side of thesheet-form material.

FIG. 8 illustrates another variation of the above-described method. Forinstance, rather than form hook-shaped fastener elements where discreteprojections are formed while molding engageable heads, mushroom-shapedfastener elements are formed where discrete projections and engageableheads are not simultaneously formed and molded, respectively. In thiscase, the mold roll 304 a contains an array of miniature, stem-shapedmold cavities extending inward from its periphery for molding thefastener elements. After the solidified upstanding stem elements arestripped from their fixed cavities, the product is fed into a second nip318 between a heated rotating roll 320 and a second counter-rotatingpressure roll 322. Heat from rotating roll 320 permanently deforms stems324 to form overhanging heads 326. The fastener elements on thecompleted fastener product 312 are now suitable for releasablefastening.

The gripping elements may be formed of a relatively low durometer resinsuitable for gripping, such as SANOPRENE rubber, thermoplastic elastomer(TPE) or the like. Preferably the gripping element material has ahardness of around 40-50 Shore A. Preferably, the gripping elements areexposed on the non-fastening side of the fastener strip as spaced-apartfeatures each surrounded by exposed substrate. The gripping elements maybe arranged in any suitable pattern, and can even form graphics, text orlogos. The gripping elements may be formed of a resin of a differentcolor than the substrate, such that the gripping elements provide avisual indication of a gripping zone.

The fastener elements may be formed from a resin with propertiessuitable for repeatedly bearing required fastening loads without unduedistension or premature loop release. Polypropylene has been found to bea suitable resin, and may have a hardness significantly greater, asmolded, than the gripping element material. The substrate material maybe a preformed non-woven or knit, for example, such as Loop 3905available from Velcro USA.

While a number of examples have been described for illustrationpurposes, the foregoing description is not intended to limit the scopeof the invention, which is defined by the scope of the appended claims.There are and will be other examples and modifications within the scopeof the following claims.

1. A method of making a touch fastener product, the method comprising:feeding flowable resin and a preformed, sheet-form substrate into a nipbetween two rotating rolls, the rolls including a mold roll defining anarray of cavities extending inward from a peripheral roll surface;forming a base layer of the resin laminated to a first side of thesubstrate under pressure while molding an array of discrete projectionsof the resin in the cavities, such that the projections and the baselayer form a seamless mass of the resin; forming engageable heads of theresin on the projections, thereby forming an array of fastener elementsextending from the base layer; and forming an array of discrete regionsof the resin on a second side of the substrate opposite the projections,by pressing resin through apertures defined in the substrate by pressurein the nip, each discrete region comprising exposed resin surrounded byexposed substrate.
 2. The method of claim 1 wherein the engageable headsare formed while molding the discrete projections.
 3. The method ofclaim 1 wherein the engageable heads are mushroom-shaped radialextensions of the discrete projections.
 4. The method of claim 1 furthercomprising, prior to feeding the sheet-form material into the nip,perforating the sheet form material to form the apertures.
 5. The methodof claim 1 wherein the apertures are arranged in an evenly spaced array,such that the formed discrete regions of resin are evenly spaced.
 6. Themethod of claim 1 wherein at least some of the discrete projections areformed directly opposite the discrete regions of resin.
 7. The method ofclaim 1 wherein the discrete regions of resin are formed as extensionsof a layer of resin formed on the first side of the material.
 8. Themethod of claim 7 wherein the base layer from which the projectionsextend, and the resin layer from which the discrete regions extend, areseparated by a lane of resin-free substrate.
 9. The method of claim 7wherein the base layer from which the projections extend, and the resinlayer from which the discrete regions extend, substantially overlap,such that the base layer overlays the resin layer from which thediscrete regions extend.
 10. The method of claim 1 wherein feeding theflowable resin comprises feeding both a first resin that forms theprojections and the base layer of resin laminated to the first side ofthe substrate, and a second resin that forms the discrete regions ofresin on the second side of the substrate.
 11. The method of claim 10wherein the first and second resins are fed into the nip as spaced-apartflows of resin.
 12. The method of claim 10 wherein the first and secondresins are fed into the nip to form overlapping resin layers.
 13. Themethod of claim 10 wherein the second resin is of a lower durometer thanthe first resin.
 14. The method of claim 1 further comprising, afterforming the base layer of the resin and forming the discrete regions ofthe resin, severing the touch fastener substrate to form separatefastening tabs, each tab carrying a segment of the base layer and agroup of the discrete regions.
 15. The method of claim 1 wherein resinis pressed through the apertures such that the formed discrete regionsof resin project beyond a plane of the exposed substrate at the secondside of the substrate, forming bumps of resin.
 16. A touch fastenerproduct comprising: a flexible, sheet-form substrate; a base layer ofresin laminated to the substrate; a multiplicity of fastener elementsextending from the base layer, each fastener element comprising adiscrete projection with an engageable head of resin, the fastenerelements and base layer form a seamless mass of the resin; and amultiplicity of discrete regions of exposed resin each surrounded byexposed sheet-form material on a second side of the substrate oppositethe projections and extending from a layer of resin laminated to thefirst side of the substrate.
 17. The touch fastener product of claim 16wherein the discrete regions of resin are of the same seamless mass ofthe resin as the fastener elements and base layer.
 18. The touchfastener product of claim 16 wherein the layer of resin from which thediscrete regions extend is of a lower durometer than the base layer ofresin from which the fastener elements extend.
 19. The touch fastenerproduct of claim 16 in the form of a fastening tab having a distal endat which the layer of resin from which the discrete regions extendterminates.
 20. The touch fastener product of claim 16 wherein thediscrete regions each comprises a resin feature extending out of thesubstrate.